Magnetic field resonance-based power transmission has conventionally been proposed (see Patent Document 1, for example). There has also been proposed a method for designing an easy-to-design and easy-to-manufacture non-contact power transmission apparatus (see Patent Document 2, for example). In the method for designing, a non-contact power transmission apparatus disclosed in Patent Document 2, the relationship between the input impedance and the frequency of a resonant system is put on a graph. Based on this, the frequency of an AC power source is set between a frequency at which the input impedance takes a local maximum value and a frequency that is higher than the frequency at which the input impedance takes the local maximum value, at which the input impedance takes a local minimum value.